Are you supposed to leave your airgapped Core permanently trying to sync?

[takuma sato]

Suppose you have the classic 2 laptop setup where one acts as an online node to create the raw unsigned transaction (now I think this can be done easily with the PSBT file) and then the other laptop as the airgapped Core instance where you load the PSBT file and sign it, to then send it back to the online one to broadcast.

Anyway, my question is: How does your airgapped Core instance look like? Do you just leave it trying to sync forever? Is it possible to stop it from trying to sync?

Perhaps some work could be done in this direction? to have an "airgap mode" where you just load Bitcoin Core as a storage box of private addresses to sign PSBTs and control the funds with watch only addresses in the online laptop? I think this is the idea of "Armory" but I only trust the Core software at this point because it's the most peer reviewed one so I would like a Core solution for this one. As far as PSBT tutorials I only see them aimed for hardware wallets but not for airgapped computers which imo is a more powerful tool. I will have to try in testnet exactly how it works. I assume when creating a PSBT file on the GUI you are asked to manually enter where the change will go so you enter an address there that you own on your offline wallet to get the change.

Anyway I would like to know someone here uses this 2-Core airgapped setup and how do you do it.

[ranochigo]

Yes. It makes no difference whether it is trying to synchronize or not. Your offline Core node's primarily purpose is to only sign transactions with the information given using the PSBT files.

We'll have descriptors soon so it should be easier to import descriptors within the online Core instance.

[takuma sato]

Yes. It makes no difference whether it is trying to synchronize or not. Your offline Core node's primarily purpose is to only sign transactions with the information given using the PSBT files.

We'll have descriptors soon so it should be easier to import descriptors within the online Core instance.

Is there nothing planed to refine this "airgapped state"? The software constantly trying to do something to no end when it's not needed wastes resources. It's like having an offline computer you will never plug constantly running ping. In this sense there is some optimization that could be done. Any work in this direction is good imo. Most computers that don't have NSA chips on them are old, so considering you would want to use one of these to create and sign transactions, having a "lightweight offline Core" mode of sorts would be cool. Like a HW wallet with the Core interface and knowing it's proper peer reviewed and running on a librebooted laptop.

[achow101]

You can turn off all network connectivity by clicking on the connections icon in the bottom righthand corner and that will instruct Bitcoin Core to not try to make any network connections. Then it isn't constantly "trying to sync". The out of sync modal will remain since it is unrelated to the network connection status, but that does not mean it is actually doing anything in the background.

[takuma sato]

You can turn off all network connectivity by clicking on the connections icon in the bottom righthand corner and that will instruct Bitcoin Core to not try to make any network connections. Then it isn't constantly "trying to sync". The out of sync modal will remain since it is unrelated to the network connection status, but that does not mean it is actually doing anything in the background.

Right then I will click the icon. But I have another question: During the install of Bitcoin Core it says you must have 450 GB at least (or whatever size at the time for a full download). Since I have never attempted to install it on a drive with less size than that and the size I want to use is just a small 100 GB HDD for this: will Bitcoin Core let me install anyway? Basically I only need the space required for the OS, a few extras and Bitcoin Core (the software not the blockchain) so im not even bothering with SSD.

[achow101]

Right then I will click the icon. But I have another question: During the install of Bitcoin Core it says you must have 450 GB at least (or whatever size at the time for a full download). Since I have never attempted to install it on a drive with less size than that and the size I want to use is just a small 100 GB HDD for this: will Bitcoin Core let me install anyway? Basically I only need the space required for the OS, a few extras and Bitcoin Core (the software not the blockchain) so im not even bothering with SSD.

Yes. It is simply a warning informing the user of the disk space requirements if you want the full blockchain, but there is no hard requirement that would make the software not run if it there isn't that much space available. Of course it will shut itself down if it actually runs out of disk space, but that's entirely different.